Nanostructure research and electron microscopy

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Microstructure of epitaxial semiconductor thin films

“III–V” semiconducting materials have many applications such as optoelectronic devices, high-mobility field effect transistors and sensor technologies. The performance of working devices made of III-nitride semiconductors can be influenced by the microstructure of the thin films and by the arrangements of atoms at the interfaces as well as by the crystal polarity of nanostructures and heterostructures. For industrial applications, the materials are usually produced as epitaxial thin films on a suitable substrate. However, due to lattice mismatch a various defects are formed in the thin films during material growth. The research activity of the group aims at the study of structural defects in “III–V” semiconducting thin films grown by ion-beam assisted MBE (in cooperation with AG Gerlach). The thin films are studied by combination of state-of-the art transmission electron microscopy and theoretical image simulation. The local structure at the interfaces are investigated by a special developed imaging technique for direct imaging of light elements.

Selected Publications

  • B. Rauschenbach, A. Lotnyk, L. Neumann, D. Poppitz, J.W. Gerlach
    Ion beam assisted deposition of thin epitaxial GaN films
    Materials 10 (2017) 690-702

  • D. Poppitz, A. Lotnyk, J.W. Gerlach, J. Lenzner, M. Grundmann, B. Rauschenbach
    An aberration-corrected STEM study of structural defects in epitaxial GaN thin films grown by ion beam assisted MBE
    Micron 73 (2015) 1-8

  • D. Poppitz, A. Lotnyk, J.W. Gerlach, B. Rauschenbach
    Microstructure of porous gallium nitride nanowall networks
    Acta Materialia 65 (2014) 98-105

  • A. Lotnyk, D. Poppitz, J.W. Gerlach, B. Rauschenbach
    Direct imaging of light elements by annular dark-field aberration-corrected scanning transmission electron microscopy
    Appl. Phys. Lett. 104 (2014) 071908